4. What hypotheses do you know concerning the origin ofthe Universe?
5. Is there a 100% agreement between the scientists on the problem?
6. What do surveys ofthe stellar system structure show?
7. Why has the existence of super-clusters long been conjectured?
8. What investigation tools did scientists use in the past?
9. What investigation tools gave the most important information for cosmology?
10. What hypotheses concerning the voids in the Universe do you know?
• Match each word in column I with its 1
emergence, to presume, to verify, to conjecture, at random, to lack, to clarify, similarity, evidently, to conceive the idea
synonym in column II.
II
to make clear, to form in the mind, to confirm, to suppose, to guess, not to have, obviously, likeness, appearance, without reason or aim
• Choose a proper word and complete the sentences.
1. How soon after the Big Bang did matter begin to (cluster/coalesce/ coincide) into the stars and galaxies?
2. Large-scale surveys have (viewed/violated/verified) the existence of superclusters of galaxies.
3. The existence of superclusters has long been (converted/conjectured/ connected).
4. The original distribution of matter is (singled out/smeared out) by evolutionary "mixing".
5. An understanding of the largest structures in the universe will (clarify/ clean/coincide) the processes that give rise to structures of all dimensions.
6. Astronomers and cosmologists are much preoccupied these days with explaining the (convergence/emergence/exislence) and distribution of aggregates of matter in the Universe.
CLASSWORK
READING (4B)
» Skim the passage rapidly (3 min.) and answer the questions.
1. What hypotheses concerning the origin of the Universe were put forward?
2. Which of the hypotheses is supported by observations?
3. What assumption is made about the voids of the Universe?
It has become clear from the red-shift surveys that the present-day distribution of galaxies is highly inhomogencous out to a distance of several hundred million light-years. * // seems probable that the inhomogeneity extends out to billions of light-years and characterizes the entire universe. We must assume, however, that the universe may contain much matter that is nonluminous. The possible existence and volume of such matter is currently the subject of wide speculation.
There are two competing hypotheses. The more conventional model assumes that individual galaxies arose out of a nearly homogeneous primordial soup. *The main trouble with this model is explaining how the universe proceeded from its smooth state to the state in which matter was gathered into galaxies. The model assumes that once galaxies formed, small irregularities in their distribution would slowly be amplified by the operation of long-range gravitational forces. The end result of such amplification would be the superclusters seen today.
Л competing theoretical explanation was suggested in 1972 by two Russian astronomers, Yakov Zcl'dovich and Rashid Sunyaev. In their model the gas of the early universe did not condense into stars and galaxies immediately. Instead, slight but very-large-scale irregularities in the general distribution of the gas grew larger in response to gravitational attraction and became increasingly irregular. Eventually, the gas became dense enough to collect into vast sheets of material, which then fragmented into galaxies. *Accordingtothis hypothesis, clusters and superclusters form first as concentrations of gas, and only then do galaxies appear.
Do either ofthese models find support in the observations wc have made of superclusters? *Sincc the Zel'dovich-Sunyacv model requires all galaxies to have formed in clusters or superclusters, field galaxies, or random stragglers, should be rare. If the conventional model is correct and galaxies can arise almost anywhere at random, only later to be shepherded by gravity into groups or clusters, stragglers should be rather common. Actually, the only populations of isolated galaxies we have discovered in our red-shift surveys are galaxies scattered within the boundaries of superclusters. Moreover, the voids are genuinely empty. In sum, the observed distribution of galaxies within superclusters and the existence of huge voids between superclusters are entirely consistent with the Zel'dovich-Sunyaev model.
• Explain the way you understand the italicized words and phrases in the passage.
• Give an English-Russian translation of the sentences marked with an asterisk.
• Give a free translation of the text below.
ЗВЕЗДА В 2.500 СОЛНЦ
Астрономы Висконсинского университета (США), анализируя данные, полученные с помощью искусственного спутника Земли, подтвердили, что в газовой туманности Тарантул (Tarantula Nebula) в Большом Магеллановом облаке (Large Magellanic Cloud) существует сверхмассивная звезда. Ученые, наблюдавшие ее ранее с использованием оптических телескопов, высказывали предположение, что масса этого небесного тела больше массы Солнца в 200—1.000 раз, однако спутниковые наблюдения вносят поправку — в 2.500 раз!
Звезда расположена в центре самого яркого облака ионизированного водорода — газовой туманности Тарантул, светимость которой в сто миллионов раз выше светимости Солнца.
HOMEWORK
(to be done in writing)
1. Translate into Russian.
1. The most important information for cosmology must have been collected by telescopes that gather visible and near-visible light.